Feeding mechanism for sewing machines



Aug. 4, 1931. A. J. woHLPAR-r FEEDING MECHANISM FOR SEWING MACHINES Filed Jan. ll, 1927 5 Sheets-Sheet l H N HUM Jmnmmlll w 'ZZ Aug. 4, 1931. A. 1. woHLPART FEEDING MECHANISM FOR SEWING MACHINES Filed Jan. l1, 1927 3 Sheets-Sheet .will FW l /l /l :l I

ug- 4, 1931- A. .1. WOHLPART 1,817,727

FEEDING MECHANISM FOR SEWING MACHINES Filed Jan. ll, 1927 3 Sheets-Sheet 3V ing machines,

Patented ug. 4, `1931 UNITED STATE-s PATENT OFFICE AUGUST J. woHLPAivr,

comm, og CHICAGO,-

OF NEW YORK, N. Y., ASSIGNOB T0 UNION SPECIAL MACHINE ILLINOIS, A. CORPORATION or ILLINos FEEDING- MECHANISM FOB SEWING- IMACHIIINESy 'v .Application mea January 11,1927. serial 110.160,432.

The invention relates to new and useful improvements in feeding mechanism for sewand more particularly to a feeding mechanism having what is commonly referredl to .asy four motions.

to' tol provide a Ari object of the invention feeding mechanism of the above type wherein `ering the the feed dog is moved back'and forth by a member rotating in a circular path about a lfined center, and wherein said feed'dog is raised and lowered by a member rotating 1n a circular path about the same fixed center.

A. further object of the invention is to provide a feeding mechanism of the above type wherein the eccentric member for raising an lowering the feed dogis so positioned as to be substantially directly above its connection with the feed'bar, which connection with the feed bar partakes of all of the movements of the feed dog.

A still further object of the invention is to provide a feeding mechanism of the above type wherein the means for raising and lowfeed dog` includes a strap or link connected at one end to a part rigidly attached to the feed bar, and connected at'its other end to the actuating member rotating in a circular path about a fixed axis.

A still further object of theA invention is to provide a feeding mechanism' of the above type wherein the' feed dog is moved back and forth by a link connected at one end to the feed rocker, and at its other end to the actuating member therefor rotating in a circular path about a iX'ed center. 'i i These and other objects will yin part be obvious and will in part be hereinafter more fully disclosed.

in the drawin lustration one em Figure l is a through the work support and su porting frame beneath the same, showing tllie main shaft and a front view of the feed .dog actuating mechanism;

Fig. 2 is a view partly in section and partly in end elevation showing the actuating means for the feed rocker;

Fig. 3 is a view partly in section and partly in end elevation showing the disk for adjustodiment of the invention-,-

longitudinal sectional viewg nection of t ably supporting the member which travels in a circular path and oscillates the feed rocker;

Fi 4 is `a sectional view on the line 4 4 of Fig. 2; z.

Fig, 5 is a sectional View Qn the line 5-5 of Fig. l;

Fig. feed bar and the means for movin the feed dog back and forth with the feed tgiog at front end of its stro e;

Fig. 7 is a view similar to Fig. 6,I but showin the feed dog at the rear end of its stroke ;v

' ig. 8 is a view showing more or lesjs diagrammatically the means 'for raising and lowering the feed dog with the feed dog raised to psition. for feeding the material;

Fig. 9 is a similar view, but feed dog at the rear end of its stroke 5 Fig. 10 is a similar view, but showing the feed dog as having 'moved beneath the work support and in position to be retracted;

Fig. 11 is a vlew showing the feed dog as` substantially retractedand ready for eleva- 6 is'aview showing thegfeed dog, thev showing the the I tion to its initial vstarting point for feeding the material, and v Fig. l2 is a diagrammatic view the path of travel of the feed dog.

The invention is directed to a feeding mechanismvfor sewing machines, and more particularl to a feedlng mechanism wherein the fee dog is given four motions; that is, it is raised into enga ement with the material, then moved for eeding the material, then moved downwardly to release the material, and then returned to its initial position for raising into engagement with the material. The lfeed dog `is mounted on the feed'bar connected to a feed rocker of the usual type. This feed rocker is oscillated by an arm which-is rigid with the rocker, and. connected at itsouter end to a link which in turn is connected to a crank pin showing lcarried on the end of the main shaft, and

preferably adjustable radially. of the shaft. This crank pin travels in a circley about the axis ofthe shaft as a center. This actuat for moving the feed 'dog back and forth, owing to the .crank crossing the center line passing through the pivotal cone link to the eed rocker and the ing mechanism center of the shaft, will ive -a dwell to the feed do at .both ends o its reciprocation.` The fee dog is raised and lowered by an eccentric on the main shaft. Cooperating with this eccentric is an eccentric strap which is connected at its lower end to a bracket which is fixed to the feed bar. The point of connection of the eccentric strap with the bracket will partake of all the movements of the feed do The eccentric as it rotates, will cause the racket to be raised and lowered, and this is what imparts the rising and falling movements to the feed dog. `The center of the eccentric as it rotates, crosses a line passing through the center ofthe shaft, and the connection of the eccentric strap-to the bracket of the feed bar. This line willl shift as the feed dog moves back and-forth'. The resulting eifecton the pathof Vmovement of the feed dog is, that the feed dog will move'forward to feed the material ina sub'- Y stantially flat or straight vpath parallelle-With the work support. AAs the feed dog reaches that the crank the rearend of its stroke,` it will@V quickly move downwardly beneath the work support while the feed dog issubstantialjly i'dlleand then the feed. dog is retracted and .brought back to: the position for raising 1 .the Yfeed dog into-,engagement with the Inateria'l'.v lThe feed dog is raised into engagement'with the material substantially whlle vit is at a.. dwell at the forward end of its stroke.

Referrin'gvmore in detail to thevdrawings,

- I haveshown my' improved feeding mechanism as'elnbodied in a sewing machine having a bed v1, with upstanding bearing lugs 2 and 3. Mounted on these bearing lugsis a cloth plate 4 provided with a throat plate 5. The throat plate 5 is in turn provided with feed slots 6. The feed dog 7 1s rovided in sections which pass up throng the feed slots 6.

` This feed dog 7 is mounted on a feed'bar 8. The feed bar 8 is pivoted at 9 to a feed rocker 10. The feed rocker 10 is pivoted at a 11 to the bed 1. The feed rocker 10 is provided with an arm 12 which is rigid therewith, and which extends forwardly from the feed rocker. A mainv shaft '13 is mmmted to rotate in suitable bearings in the supportin l lugs 2 and 3. Thismain shaft carries a dis r 14 in its forward end, which is secured thereto by a set screw 15. The disk 14 has a slot 16 extending diametrically across the same. This slot is dove-tailed in cross section,'and

a block 17 is mounted in thel slot. Said blockcarries a crank pin -18. The blockis shifted in the slot b an adjusting screw 19. A link .20 ispivote 'at its lower end to the arm 12 of the feed rocker by `a pivot bolt-21. vThis link 20 engages the crank pin 18. On the crank pin is a sleeve 22 which -is held thereon by meaisatnut 23, and the link 20 engages this sleeve.

The feed bar 8 is made in two sections, 8a

feed do and the feed rocker may be varied. l

`This a ords,an easy way of shifting the working position or path of travel of the 4feed dog without changing the character or extent of travel. On the main shaft 13 is an I eccentric 26. Cooperating with the eccentric V26 `is an eccentric strap 27. The eccentric strap 27 is pivoted at 28 to the arm 8d. The eccentric26 has a center which moves in a circularpath about the center of the main shaft 13. v From F igures' 6 and 7, itwill be apparent in which moves the feed dog back and fortli will cross a line passing through the center of the shaft, and the piv otal connection of the link actua'ted by the crank pin to the feed rocker arm, when the feed dog is at the forward end'of its stroke.

" It will also be apparent that the crank pin will again cross this line passing through the center of the shaft and the pivotal connection of the link to the feed rocker. This occurs when the feed dog is at thl rear end o'f its stroke. When the crank pi is crossing this. line referred to, there are practically no movements im artedto the feed rocker; that is, the feed roc er is substantially idle. This occurs whenA the feed dog is at the ends of its reciprocation.

In Figures 8 to 11, the feed dog and the means for raising the same have been shown in various ositions, and in Fig. 12, the path of travel of the feed dog has been indicated diagrammatically. When the parts are in the position shown in Fig. 8, the feed dog is at a position indicated at a (Fig. 12) in its path of travel. Theeccentric 26 is turning in the direction of the arrow in this figure. 'As the feed dog moves to the position shown in Fig. 9, the eccentric has rotated so as to maintain the feed dog in its raised osition during its feed travel. The center o the eccentric is above the center of the shaft during this period, and of course,

ralse the feed dogv the feed dog is traveling the center is travel- 1n 1n a curved path. This would tend to from the front end to the' rear end of its Y Y stroke, the pivotal connection 28 between the Aeccentric strap and the arm carried by the feed-bar, alsoswin s in the arc of a circle. The pivotal connection 28 moves from a point at one side of a vertical plane to a point at the other side of a vertical plane, and its path of the drawings.

eccentric 26 moves so as to raise the feedl dog'.` at each end .of-its-ig of the feed dog` during the entire feedin Lawyer ward curving of the path -of travel of the pivotal point 28 offsets the upward curved path of travel of the center ofthe eccentric, so that the feed bar moves in substantially a straight line duringlits feeding stroke. dogis at t e rear en of its stroke, itis substantially at a dwell, and during this time the eccentric 26 moves so as to lower the feed dog. This is clearl apparent from Fig. l0

hen the feed do is returned, the center of the eccentric is neath the center of the main shaftl, and its downward curved path of travel might be said to be added to the downward curved path of travel of the pivot point 28. During this time, the feed dog is traveling from b to b (Fig. 12) in its ath. whether this 'pat is a strai ht line or a curved line in between the points and vb (Fig. 12),'

og. it is substan:

as the feed dog is idle. When the feed d is at the front end of its stroke, tially at a dwell, and during this time, the

The dwell to the feed dog stroke is brought about through the cran-k and link connection to the arm which is rigid with the feed rocker,v pointed out.- This particularmeans for oscillating the feed rockerand imparting feedlng movements to the feed dog, together with lthe particular means described for raising and lowering the'fee'd dog, bring about the travel hich is substantiallgI straight stroke o From the above it wil be apparent that I. have providedA a feeding mechanism wherein the feed dog is positivelyraised and lowered by an eccentrlc and an eccentric strap. The eccentric-'is located directly beneath the feed bar, and the eccentric strap is substantially vertical,'so that when the feed do is raised into engagement with the materia it is raised by a direct lift 'of the eccentric, and when it is lowered, it is lowered by a direct downward pressure `on the feed bar. This produces a feeding mechanism wherein the feed dog has though the machine be driven at hlgh speed. It will be further noted from Figs. 8 to 11 inclusive that the shaft rotates in a counterclockwise direction as viewed in these figures,

and, therefore, the points of contact betweenv the eccentric and the eccentric strap above the axis of the main shaft are continually moving in a counterclockwise direction. It will also be noted thatl the eccentric strap during the movements of the feed dog back and `forth oscillates shaft. The points of contact between the eccentric strap and the actuating eccentric which are located above the axis of theshaft travel first in a clockwise directionand then in a counterclockwise direction as said strap oscillates. Inasmuch as the lower end of the eccentric strap as viewed When the feed It makes no difference at the upper tric, and there is as has already been.

the dog.'

a fixed path'of travel. even about the center of thev in Figs. 5 and 8 to 11 inclusive is moving rearwardly during the active feedv stroke of the feed bar, points of contact with the eccentric strap abovethe center of the shaft are moving in a counterclockwise direction 0r in the same direction that the points of contact on the eccentric above the center of the shaft are traveling during this portion of the feed stroke. In other words, when the feed dog is raised into Contact with the material and is working against the heavy spring pressure ofthe presser foot it is doing its real work. It lifts the presser foot, holds it lifted so as to lift the fabric off from the throat plate and moves rearwardly carrying the fabric with it. At this time during this heavy wear on the eccentric, the eccentric strap,- as noted,

direction as tiie upper portion of the eccenlittle or no movement bethe ortion is traveling in the same tween the eccentric strap and the. eccentric during this time when there is a heavy lifting strain imposed upon the eccentric. Whe'ii the feed dog is returning it is free frompressure and then it is that the eccentric'strap moves inl an opposite direction from the direction of: rotation of the eccentric at the upper side ofthe shaft.. By this arrangement of the eccentric strap in conjunction with a shaft rotating as shown and described the Wear 0n the eccentric and eccentric strap is reduced to a minimum.

It is obvious that minor changes in the details of construction may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire tosecure. by Letters-Patent, is-

1. A feeding mechanism for sewing machines comprising a main shaft, a feed bar,

a feed dog rcarried by said feed bar, a feed rocker to which said feed bar is pivoted, means actuated by the main shaft for oscillating said feed rocker, an eccentric on said main shaft for raising and lowering said feed bar, an eccentric strap cooperating with said eccentric, an armcarried by said feed lbar and projecting beneath said eccentric to which said eccentric strap is connected, said eccentric strap being disposed so as to move its lower end from one side of a vertical line passing through the center of the shaft tothe other side thereof, and means for rotilting-said main shaft so that the center of I the eccentric moves 1n a direction opposed to the feed when with the material and moving in the direction of feed to feed the same.

the feeddog is in engagement `2. A feeding mechanism for sewing' mal chines comprisinga main shaft, a feed bar, a feed dog carried by said feed bar, a feed rocker to which said feed bar is pivoted, means actuated by the main shaft for oscillating said feed'Jrocker, an eccentric on said main shaft lying in a vertical plane containing the line of feed, an arm rigidly connected to said' feed bar between the feed dog and' 5 the rocker and extending beneath said eccentric, an eccentric strap cooperating with said eccentric and connected to the free end of said arm for raising and lowering the feed dog, 4said connection between the arm and the eccentric strap being movable from a point at one side of a vertical line passing through the center of the shaft to a pointat the other side thereof during the feed stroke of the feed dog, and means for rotating said shaft so that the center of the eccentrlc moves in a direction opposed to the feed when the Vfeed dog is in engagement with the material and moving in the direction of feed to feed the same whereby said feed dog is caused to move in a substantially straight line during the feeding of the material and the bearing points of the eccentric strap on the eccentric are traveling with the eccentric during the feed stroke.

In testimony whereof, I aix my signature.

AUGUST J. WOH'LPART. 

